In one embodiment, a direct-contact steam condenser includes: a steam cooling chamber; a inflow part; a plurality of first spray nozzles; and a water reservoir part. The inflow part leads turbine exhaust gas containing steam and non-condensable gas in a substantially horizontal direction into the steam cooling chamber. The plurality of first spray nozzles are disposed in the steam cooling chamber to be connected to a plurality of spray pipes extending along the direction in which the turbine exhaust gas is led in, and spray cooling water to the turbine exhaust gas. The water reservoir part is disposed under the steam cooling chamber to store condensate water that is condensed from the steam by the spraying of the cooling water.